linux-kernel - Re: [linux-sunxi] Re: [PATCH 4/6] dt-bindings: display: bridge: Add ICN6211 MIPI-DSI to RGB convertor bridge

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Date:   Tue, 19 Mar 2019 13:18:21 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     Chen-Yu Tsai <wens@...e.org>
Cc:     Maxime Ripard <maxime.ripard@...tlin.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Michael Trimarchi <michael@...rulasolutions.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>,
        linux-amarula@...rulasolutions.com
Subject: Re: [linux-sunxi] Re: [PATCH 4/6] dt-bindings: display: bridge: Add
 ICN6211 MIPI-DSI to RGB convertor bridge

On Tue, Mar 19, 2019 at 8:29 AM Chen-Yu Tsai <wens@...e.org> wrote:
>
> On Tue, Mar 19, 2019 at 12:58 AM Jagan Teki <jagan@...rulasolutions.com> wrote:
> >
> > On Fri, Mar 15, 2019 at 7:04 PM Maxime Ripard <maxime.ripard@...tlin.com> wrote:
> > >
> > > On Fri, Mar 15, 2019 at 06:38:23PM +0530, Jagan Teki wrote:
> > > > ICN6211 is MIPI-DSI/RGB converter bridge from chipone.
> > > > It has a flexible configuration of MIPI DSI signal input
> > > > and produce RGB565, RGB666, RGB888 output format.
> > > >
> > > > Add dt-bingings for it.
> > > >
> > > > Signed-off-by: Jagan Teki <jagan@...rulasolutions.com>
> > > > ---
> > > >  .../display/bridge/chipone,icn6211.txt        | 36 +++++++++++++++++++
> > > >  1 file changed, 36 insertions(+)
> > > >  create mode 100644 Documentation/devicetree/bindings/display/bridge/chipone,icn6211.txt
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/display/bridge/chipone,icn6211.txt b/Documentation/devicetree/bindings/display/bridge/chipone,icn6211.txt
> > > > new file mode 100644
> > > > index 000000000000..7f13efd7ee7f
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/display/bridge/chipone,icn6211.txt
> > > > @@ -0,0 +1,36 @@
> > > > +Chipone ICN6211 MIPI-DSI to RGB Convertor Bridge
> > > > +
> > > > +ICN6211 is MIPI-DSI/RGB converter bridge from chipone.
> > > > +It has a flexible configuration of MIPI DSI signal input
> > > > +and produce RGB565, RGB666, RGB888 output format.
> > > > +
> > > > +Required properties for RGB:
> > > > +- compatible: must be "chipone,icn6211" and one of:
> > > > +  * "bananapi,icn6211"
> > >
> > > Why is that compatible needed?
> >
> > chipone,icn6211 - generic compatible bridge controller IC
> > bananapi,icn6211 -  compatible for icn6211 bridge using on bananapi panel
> >
> > I hope this would be proper bindings in terms of controller IC with
> > associate device, anything wrong? Infact I used similar reference from
> > Ilitek Bananapi panel from here
> > Documentation/devicetree/bindings/display/panel/ilitek,ili9881c.txt
> >
> > This is what I understood based on dt-binding, correct if I'm wrong.
> >
> > ilitek,ili9881c - generic ilitek,ili9881c compatable
> > bananapi,lhr050h41 - compatible for bananapi panel associated with
> > this ilitek IC
>
> ili9881c is an LCD driver chip with a MIPI DSI interface. It directly
> drives the LCD panel, not outputting some RGB stuff. So it is a binding
> and driver for a panel, not a bridge in your case.
>
> > >
> > > > +- reg: the virtual channel number of a DSI peripheral
> > > > +- reset-gpios: a GPIO phandle for the reset pin
> > > > +
> > > > +The device node can contain following 'port' child nodes,
> > > > +according to the OF graph bindings defined in [1]:
> > > > +  0: DSI Input, not required, if the bridge is DSI controlled
> > > > +  1: RGB Output, mandatory
> > >
> > > Your example doesn't have that input port
> >
> > Yes, I intentionally did this by referring existing bridge binding.
> > Documentation/devicetree/bindings/display/bridge/toshiba,tc35876*.txt
> >
> > Do we really need? since the input port can be part of panel binding.
>
> How could the input port of _your_ _bridge_ be part of the panel binding?

Here the panel is from another vendor say bananapi, so the binding of
that part could be already covered ie is what I mean.

Since I mentioned I took the reference binding from another bridge. It
has similar structure of binding / example.
arch/arm/boot/dts/exynos5250-arndale.dts
Bridge example binding:
Documentation/devicetree/bindings/display/bridge/toshiba,tc358764.txt
Panel example binding mentioned here
Documentation/devicetree/bindings/display/panel/boe,hv070wsa-100.txt